1. Field of the Invention
The present invention relates to switching power supply apparatuses and, in particular, relates to switching power supply apparatuses that repeatedly invert a voltage applied to a primary side of a transformer by using switching elements and supply a voltage excited in a secondary side of the transformer to a load via a rectifier diode.
2. Description of the Related Art
An example of a conventional switching power supply apparatus is disclosed in Japanese Unexamined Patent Application Publication No. 8-51777. In Japanese Unexamined Patent Application Publication No. 8-51777, a diode and a capacitor, which are connected in series with each other, are connected in parallel with a feedback winding of a transformer and a resistor is connected in parallel with the capacitor. Here, the cathode of the diode is connected to one end of the feedback winding and the anode of the diode is connected to the capacitor. The thus-connected diode, capacitor, and resistor form a snubber circuit and a surge voltage that arises in the feedback winding due to ringing is suppressed by the snubber circuit.
However, in this example of the background art, there is a problem in that energy absorbed by the capacitor in order to suppress the surge voltage is accumulated as charge and then consumed by the resistor and therefore electrical power loss is large.